Breather for internal-combustion engines.



L. H- COBB.

BREATHER FOR INTERNAL COMBUSTION ENGINES.

, APPLICATION FILED MARJZfi, 1914.

Patented Jan. 12, 1915.

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0.. FPHoTc-LITHQ. WASHINGTON. D. C.

STATES EN FFTQ.

LYMAN H, COBB, OF FITCI-IBURG, MASSACHUSETTS, ASSIGNOR T MARY ELIZABETH JOHNSON, TRUSTEE, OF FITCHIBURG, MASSACHUSETTS.

BREATHER FOR INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Tatented Jan. 12, 1915.

Originafapplication filed January 31, 1913, Serial No. 745,325. Divided and this application filed March 25, 1914. Serial No. 827,220.

To all whom it may concern:

Be it known that I, LYMAN H. COBB, a citizen of the United States. residing at Fitchburg, in the county of WVorcester and Commonwealth of Massachusetts, have invented a new and useful Improvement in Breathers for, Internal- Combustion Engines, of which the following, together with the accompanying drawing, is a specification.

This application is a division of my copending application for patent on valve controlling mechanism for internal combustion engines, Serial No. 715,325, filed J anuary 31, 1913.

My present invention relates to breathers adapted to prevent objectionable differences between the pressures inside and outside of the crank cases of internal combustion engines.

The movements of certain internal combustion engine parts, particularly the pistons, are likely to produce such variations in pressure within the crank case as to interfere with the proper operation of the engine unless some provision is made to overcome this action.

One object of the invention, therefore, is to form a tappet and the adjacent parts of an engine in such manner as to establish communication between the interior and exterior of the crank case and so prevent objectionable variations in pressure within the crank case.

One form of the invention will be described in connection with the accompanying drawing. in which Figure 1 is a side elevation of the crank case and cylinders of a motorcycle engine, a portion of the crank case being removed to show the valve controlling: mechanism; Fig. 2 is a sectional view on the line 2-2 of Fig. 1; and Fig. 3 is a sectional view on the line 3-3 of Fig. 1.

Like reference chara cters refer to similar parts in the different figures.

The crank case 1 and the cvlinders 2 and 3 are rigidly joined in any suitable manner, the cylinders being set 60 apart about the crank shaft. An intake valve stem 4 and an exhaust valve stem 5 for the cylinder 2 are operated by tappets 6 and 7 respectively. An intake valve stem 8 and an exhaust valve stem 9 of the cylinder 3 are similarly operated by tappets 10 and 11 respectively. The valve stems are provided with spiral springs 12 confined between shoulders 13 on the valve stems and the surfaces of the cylinders and tending to maintain their respective valves in closed position.

The tappet 7 reciprocates in a bushing 14 mounted in the crank case. the tappet being held by the bushing in alinement with the valve stem 5 operated thereby. Each of the other three tappets 6, 10 and 11 are similarly mounted in bushings carried by the crank case.

The upper ends of the tappets 6, 7, 10 and 11 are provided with threaded openings into which are screwed adjusting screws 6, 7, 10 and 11, these adjusting screws being retained in any desired adjustment by lock nuts carried thereby and screwed down against the ends of the tappets. The adiusting screws serve to adjust the effective lengths of the tappets so as to move their respective valves through the proper distances.

The lower end of each of the tappets engages the external face or periphery of a ring-shaped member 15, the periphery of this ring-shaped member being provided with cams 16 and 17 for operating the tappets 6 and 7 respectively and with cams 18 and 19 for operating the tappets 10 and 11 respectivelv. The cams are. of course. located at slightly different distances from the edge of the ring-shaped member 15 so that their paths will not coincide. the lower ends of the tappets being similarly positioned so that each may lie normally within the path of the proper cam. In order to reduce friction, the cam en aging ends of the tap ets are provided with antifriction rollers 20.

One edge of the internal face of the ringsha ed member 15 is provided with gear teeth 21 and the other edge is finished to form a cylindrical bearing surface 22. The crank case 1 carries a cylindrical flange 23,

the flange being p eferably integral with the crank case. The external cylindrical face of this flange is finished to provide a bearing surface 24 to fit within the bearing surface 22, the flange 23 thus forming a bearing for the ring-shaped member 15 to rotate upon. The driving shaft 25, mounted in asuitable bearing 26 formed in the crank case, drives a pinion 27 which engages the teeth 21 of the ring-shaped member 15. The pinion 27 is secured to the shaft 25 by a screw 28 and a key 29. The internal gear wheel 15 and the pinion 27 are surrounded by a protecting flange 30 and any suitable cover may be provided to exclude dust and other foreign matter.

In order that objectionable differences in pressure within the crank case, caused by the movements of the pistons and other parts of the engine, may be prevented, the tappet 10 is hollow, the space 31 within the tappet having communication through one side of the tappet with a pipe 32 leading to a point outside the crank case, so that the space 31 within the tappet is always in communication with the outside air. Two other openings 33 are provided through another side of the tappet so as to move into and out of register with two openings 34- leading from the inner surface of the bushing carrying the tappet 10 to the interior of the crank case 1. One opening 33 and one opening 34 would be sufficient if large enough in cross section, but the number of openings shown is preferable in order that air and other gases may pass to and from the interior of the crank case with as little resistance as possible. Each time that the tappet 10 is raised by its cam 18, the openings 33 will come into register with the openings 34:, thus establishing communication between the interior of the crank case and the outside air by way of these openings, the space 31 and the pipe 32. The tappet 10 with its cam 18 thus acts to prevent objectionable changes in pressure within the crank case, or, as it is sometimes said in the art, it acts as a breather. The space 31 may be a continuation of the threaded opening provided for the adjusting screw 10, this adjusting screw serving to close the upper end of the space 31. The arrangement of the parts is such that the tappet 10 will be raised so as to interrupt communication between the interior of the crank case and the outside air at approximately the same time or slightly before the time that the movements of the pistons cease causing the exhaust gases to be expelled from the interior of the crank case or, in other words, the time at which the space filled by the gases within the crank case is at its minimum. As this space begins to increase in size, due to the reverse movements of the pistons, a partial vacuum is formed. the opening to the outside air be ing closed. After a slight vacuum has been formed in this way within the crank case, the tappet 10 is again dropped so as sud denly to reestablish communication with the outside air. This causes a sudden rush or puff of air into the crank case, the sudden current of air serving to blow all lubricant 1 away from the vicinity of the openings 3% so that it cannot be expelled with the next outward current of exhaust gases through these openings. Much of the lubricant that would otherwise be wasted is thus saved and it is also prevented from being spatter-ed upon the outside of the machine and other surrounding objects.

The shaft 25 is driven directly by the connecting rods of the engine and so the pinion 27 rotates once for each complete up and down stroke of one of the pistons. In the engine shown, each piston makes two such complete strokes during each cycle and, therefore, each valve must operate once while its piston is making two complete strokes. For this reason the number of teeth on the internal gear wheel 15 is twice as great as the number of teeth on the pinion 27, so that the gear wheel will rotate once while the pinion driving it is rotating twice.

lVhile I have illustrated the principles of my invention by showing and describing the details of one form thereof, I do not wish to be limited to such details as it is obvious that certain changes may be made within the scope of the appended claims withoutdeparting from the spirit of the invention; but

What I claim as new and desire to secure by Letters Patent is:

1. An internal combustion engine including a crank case, and means operable by the engine for alternately establishing and interrupting communication between the in terior of the crank case and the outside air.

2. An internal combustion engine including a crank case, there being an opening between the interior of the crank case and the outside air, and means operable by the engine for alternately opening and closing said opening.

3. An internal combustion engine including a crank case, and a hollow reciprocatory tappet, there being openings to connect the interior of the tappet with the interior of the crank case and with the outside air.

4. An internal combustion engine including a crank case, a hollow reciprocatory tappet, there being openings to connect the interior of the tappet with the interior of the crank case and with the outside air, and means for reciprocating the tappet to interrupt and establish communication between the interior of the tappet and one of said openings.

5. An internal combustion engine including a crank case, a hollow reciprocatory tappet, there being an opening from the interior of the tappet to the interior of the crank case and a second opening leading to the outside air, and means for reciprocating the tappet to interrupt and establish communication between the interior of the tappet and said second opening.

6. Aninternal combustion engine including a crank case, a hollow valve-operating tappet, means for operating the tappet, and a mounting having an opening in which the tappet fits and moves, the wall of the tappet having two openings, the mounting having one opening to connect one of the openings in the wall of the tappet with the outside air, and a second opening to connect the other opening in the wall of the tappet with the interior of the. crank case.

7. An internal combustion engine including a crank case, a hollow valve-operatingv tappet, means for operating the tappet, and a mounting having an opening in which the tappet fits and moves, the wall of the tappet having two openings, the mounting having one opening to maintain constant communication between one of the openings in the wall of the tappet and the outside air and a second opening to connect the other opening in the wall of the tappet with the interior of the crank case, the motion of the of the tappet into and out of register with the corresponding opening in the mounting so as to establish interrupted communication between the interior of the crank case and the outside air.

8. An internal combustion engine including a crank case, a hollow valve-operating tappet, and means for operating the tappet, there being an opening from the interior of the crank case to the outside air, the space within the tappet forming a portion of said opening, the tappet acting as a valve to open and close periodically the said opening.

Dated this twentieth day of March 1914.

LYMAN H. COBB. Witnesses:

NELLIE WHALEN, PENELOPE CoMBERBAcH.

Copies of this patent may be obtained tor five cents each, by addressing the Commissioner of Eatents,

Washington, D. C." 

